Explicit namespaces doesn't enforce namespaces

It seems to me that the type keyword should permanently enforce that a RdrName lives in a particular namespace. Currently it only acts as a syntactic marker so that type constructors which looks like variables can be included in export lists.

The following example is accepted by GHC. As A is parsed as a type constructor but later put into the data constructor namespace.

{-# LANGUAGE ExplicitNamespaces #-}
{-# LANGUAGE TypeFamilies #-}
module M ( T (type A) ) where

data T = A

class Foo a where
  type A a
  foo :: a -> Int

The fix is to track uses of ExplicitNamespaces in the AST and then use this information in the renamer.

Trac metadata

Trac field	Value
Version	8.0.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture